The present invention relates to therapeutics for the prevention and treatment of autoimmune disease, and in particular the prevention and treatment of autoimmune disease in humans through the use of luminally administered polyclonal antibody.
A progressive and maintained response by the immune system against self-components is termed autoimmunity. Normally self-tolerance mechanisms prevent the immune response from acting on self-components. However, all mechanisms have a risk of breakdown and occasionally the immune system turns on its host environment in an aggressive manner as to cause disease. This breakdown leads to the copious production of autoreactive B cells producing autoantibodies and/or autoreactive T cells leading to destructive autoimmune disease. The cellular mechanisms of autoimunity are the same as those involved in beneficial immune responses to foreign components which include antibody-dependent cell cytotoxicity, delayed-type hypersensitivity (DTH), and T-cell lympholysis.
Human autoimmune diseases can be divided into two categories: organ-specific and systemic. In organ-specific autoimmune disease, autoreactivity is directed to antigens unique to a single organ. In systemic autoimmune disease, autoreactivity is largely directed toward a broad range of antigens and involves a number of tissues. Disease in either type results from the generation of one or both autoreactive cell types (B or T cells). Autoreactive B cells leads to the generation of autoantibodies or immune complexes. Autoreactive T cells leads to the cellular DTH responses from TDTh cells or cytotoxic responses from TC cells. Some autoimmune diseases in humans and the immune response and antigen(s) involved are shown in Table 1.
The current view of the etiology of autoimmune diseases posulates that both autoreactive T and B cells exist normally in the body. Control of these cells involves immune surveillance mechanisms which can induce tolerance to these cells and/or the selective elimination of these cells. Factors which overcome immune surveillance are thought to be responsible for the proliferation of these autoreactive cells leading to autoimmune disease.
Immune surveillance can be circumvented in several proposed ways: (1) Autoreactive cells can be stimulated through molecular mimicry by cross-reactive microbial antigens. A number of viruses and bacteria have been shown to possess antigenic determinants that are identical to normal host-cell components. Thus, antibodies generated against these microbial antigens can also recognize and damage host cells. Cross-reacting antibodies to heart muscle developed after a Streptococcus infection, for example, is thought of be the cause of an rheumatic fever. (2) In some cases, foreign antigen can directly stimulate autoreactive cells. Lipopolysaccharides or viral antigens from Epstein-Barr virus (EBV) or cytomegalovirus causes the direct stimulation of certain B cells. During mononucleosis, a disease caused by EBV, a variety of autoantibodies reactive to self-components are generated. Specifically, EBV can activate B cells to produce autoantibodies to nuclear DNA and immune cells. (3) Release of antigens normally sequestered from the immune system is another example of the breakdown of immune surveillance leading to autoimmune disease. Experimentally, animals injected parenterally with basic myelin protein, an antigen primarily found in the brain, develop experimental autoimmune encephalomyelitis. (4) Expression of specific HLA alleles has been associated with autoimmune individuals. It is thought that cells expressing these HLA""s may act as a prime target for autoreactive cells. Individuals with the B27 HLA allele has a 90% increased relative risk of developing ankyosing spondylitis.
Current therapies for autoimmune diseases are not cures, but are aimed at reducing symptoms to provide the patient with a acceptable quality of life. In organ-specific autoimmune disorders, the symptoms can be corrected by the removal of the organ if possible. In some autoimmune diseases such as myasthenia gravis some success have been achieved by removing the thymus. In addition, in organ-specific autoimmune disorders, symptoms can be corrected by metabolic control with biologically active compounds. For example, hypothroidism can be controlled by the administration of thryroxine or perrrnicious anemia can be treated with injections of vitamin B12. Drugs used in most cases of autoimmune disease, especially systemic autoimmune disease, provide general nonspecific suppression of the immune system. For the most part these drugs do not distinguish between the pathological immune response and the protective immune response. Immunosuppressive drugs (e.g., corticosteroids, azathioprine, cyclophoshamide and cyclosporin) are often given to suppress the proliferation of autoreactive lymphocytes. Anti-inflammatory drugs also are prescribed to patients with rheumatoid arthritis. Unfortunately these drugs, besides not working in many patients, have very serious side-effects. The general suppression of the immune response puts the patient at greater risk to infection and cancer.
Clearly there is a significant need for agents capable of preventing and treating autoimmune diseases. It would be desirable if such therapy could be administered in a cost-effective and timely fashion, with a minimum of adverse side effects.
The present invention relates to therapeutics for the prevention and treatment of autoimmune disease. Specifically, the present invention contemplates the prevention and treatment of autoimmune disease in humans as well as other animals through the use of ligands directed to cytokines. The examples of the present invention demonstrate the production of antibodies to the proinflammatory cytokines IL-2, TNF, IL-12 and IFN-gamma (although other ligands to such cytokines are also contemplated). The examples of the present invention demonstrate a novel finding that ligands (such as antibodies) against pro-inflammatory cytokines such IL-2 or IL-12 administered orally are effective (as demonstrated in two experimental models of autoimmune disease) at delaying the onset of autoimune disease.
In one embodiment, the present invention contemplates a method of treatment, comprising: a) providing: i) a human patient who is either at risk for autoimmune disease or who has symptoms of autoimmune disease, ii) a therapeutic formulation comprising one or more ligands directed to a proinflammatory cytokine, and; b) administering said formulation to said patient. It is not intended that the present invention be limited to the type of patient. In one embodiment, the patient is a child.
The present invention is also not limited by the degree of benefit achieved by the administration of the anti-cytokine ligands. For example, the present invention is not limited to circumstances where all symptoms are eliminated. In one embodiment, said administering reduces said symptoms (e.g., the amount of autoantibody is reduced and/or the amount of pain is reduced). In another embodiment, said administering delays the onset of symptoms.
It is not intended that the present invention be limited by the route of administration. In one embodiment, the formulation is administered to the lumen of the intestine. In a preferred embodiment, said administering is performed orally. However, said administering can also be performed parenterally.
Where antibodies are the ligand employed, the present invention is not limited to the source of the anti-cytokine antibodies. In one embodiment, said antibodies are avian polyclonal antibodies (including but not limited to chicken antibodies). In one embodiment, said antibodies are purified antibodies. In the case of chicken antibodies, it is convenient that said chicken antibodies are purified from chicken eggs.
In accordance with the present invention, one or more members from the class of IL receptors or IL receptor analogues are selectively employed in soluble form to treat autoimmune patients. The present invention also contemplates using soluble tumor necrosis factor (TNF) receptors, or TNF receptor analogues, to treat autoimmune patients. In another embodiment, the method comprises treating with a therapeutic preparation comprising, in combination, both soluble TNF and soluble IL receptors.
The existence of membrane receptors to cytokines is now well-established. Many of these receptors have now been cloned and expressed in high yield. See U.S. Pats. Nos. 4,968,607, 5,925,351, 5,919,903, 5,919,456, 5,965,704, 5,945,511, 5,945,397, 5,925,735, all of which are hereby incorporated by reference.
The present invention contemplates the use of ligands (e.g., receptors, receptor fragments, antibodies and antibody fragments) directed to proinflammatory cytokines and inflammatory mediators administered to or at the lumen to treat autoimmune diseases. In one embodiment antibodies (raised in birds or mammals) against the offending inflammatory mediators are contemplated and these antibodies can be administered systemically, orally or mucosally either prophylatically or therapeutically to the patient. A variety of classes of inflammatory mediators are contemplated to be important to generate antibodies useful in the prevention and treatment of inflammatory diseases. Illustrative cytokines and inflammatory mediators are shown in Table 2. It is envisioned that ligands against these mediators would be used either singly or in combination to treat a specific disease. Combination therapies would consist of ligands to several mediators within a given pathway.
It is not intended that the present invention be limited to a particular mechanism. Indeed, and understanding of the precise mechanism by which the administration of ligands to cytokines achieves a therapeutic benefit is not necessary in order to successfully practice the present invention. While not limited to any particular mechanism, the inventors believe that cytokines play a major role in the initiation and regulation in immune responses and that the dysregulation of the cytokine network may also lead to the activation of autoreactive T cells leading to autoimmune. Preferential activation of a specific set of T cells, TH1, is thought to play a central role in the pathogenesis of a number of autoimmune diseases. T cells with the CD4 phenotype are divided into subsets referred as TH1 and TH2 based on the nature of their immune reactivity and their cytokine secretion profile. TH1 cells are associated cell-mediated inflammatory reactions and act as effector cells in infectious disease. Secreted cytokines that set the TH1 subset apart are interferon gamma, tumor necrosis factor (TNF) interleulin-2 (IL-2) and upon activation interleukin-12 (IL-12). TH1 cytokines are referred to as proinflammatory cytokines because they activate cytotoxic, inflammatory and delayed hypersensitiviy reactions. In contrast, TH2 cells are associated with helper cell finction and antibody production. TH2 cells upon activation secrete interleukins 4 (IL-4), 5 (IL-5), and 10 (IL-10). Cytokines from a TH1 cells tend to inhibit the actions of the TH2 cell and vice versa. Whether the characterization of such cells is correct or not, the data shows that the therapeutic methods (described in more detail below) result in a dramatic delay and/or reduction in autoimmune symptoms and disease.
The phrase xe2x80x9cligand directed to a cytokinexe2x80x9d is herein defined as meaning any molecule having affinity for a cytokine. Ligands can be chemically synthesized or designed by molecular evolution. Alternatively, such ligands can be known biomolecules or portions thereof (e.g., receptors, antibodies). It is not intended that the present invention be limited to the mechanism by which ligands achieve a therapeutic benefit. Ligands may be xe2x80x9cantagonistsxe2x80x9d in that they neutralize the biological impact of a secreted cytokine. On the other hand, ligands may simply block recognition of cytokines or interfere with cell function. For example, ligands may interact with a cell-surface cytokine so as to result in immune cells not participating in autoimmune phenomenon (e.g., the cells are caused to enter apoptosis, etc.).
The phrase xe2x80x9cadministered to or at the lumenxe2x80x9d is herein defined as administration that preferentially delivers compound(s) to the space in the interior of the intestines at a concentration in excess of what is found in circulation. Such delivery can be achieved by a variety of routes (e.g., oral, rectal, etc.) in a variety of vehicles (e.g., tablet, suppository, etc.). By contrast, a parenteral administeration is not designed to preferentially deliver compounds to the lumen (although some incidental delivery can take place through normal biodistribution).
The phrase xe2x80x9csymptoms of autoimmune diseasexe2x80x9d is herein defined as any abnormal symptoms than can be attributed to the generation of autoreactive B and/or T cells. For example, autoantibodies are a common symptom associated with autoimmune disease.
The phrase xe2x80x9cat risk for autoimmune diseasexe2x80x9d is herein defined as individuals with familial incidence of autoimmunity. For example, many autoimmune diseases are associated with genetic factors such as certain HLA specificities.
A xe2x80x9cproinflammatory cytokinexe2x80x9d is any cytokine that can activate cytotoxic, inflammatory or delayed hypersensitivity reactions. Examples of such cytokines are IL-2, TNF and INF-gamma. Examples of inflammatory mediators are found in Table 2.